Summary: New research shows that mammals with larger brains and stronger immune systems tend to have longer maximum lifespans. By comparing 46 species, scientists identified a clear association between longevity and expansions in gene families tied to immune function.
While brain size has long been linked to lifespan, this study highlights that expanded immune-related gene repertoires are also a major factor. Species that live longer than expected for their brain size—such as certain mole rats and bats—also exhibit increases in immune gene counts, indicating that extended lifespan is driven by broad genomic adaptations that support immune resilience and cellular maintenance.
Key facts:
- Genomic adaptation: Lifespan differences reflect large-scale changes in gene family size rather than only single-gene mutations.
- Immune link: Longer-lived mammals show expansions in gene families associated with immune system functions.
- Beyond brain size: Some small-brained species with unusually long lives also possess elevated numbers of immune-related genes.
Source: University of Bath
Why might cats often outlive dogs? Recent findings suggest that larger brains and more complex immune gene repertoires may help explain longer lifespans in some mammal groups.
An international team led by researchers at the University of Bath analyzed evolutionary differences among mammals and found that species with larger brains and greater maximum lifespan potential tend to invest more in genes linked to immune function. The study mapped shared gene families across 46 mammalian species to explore the genomic patterns connected with longevity.
The team focused on maximum lifespan potential (MLSP)—the longest recorded lifespan of any individual of a species—because average lifespan can be skewed by ecological pressures such as predation or resource scarcity. MLSP provides a clearer signal of a species’ inherent ageing potential.
Published in Scientific Reports, the analysis revealed that species with longer MLSPs tend to have larger gene families enriched for immune system functions. This pattern suggests that expansions of immune-related genes have played a major role in the evolutionary development of extended lifespan across mammals.
Examples from the study include marine mammals like dolphins and whales, which have relatively large brains and maximum lifespans around 39 years and up to 100 years respectively. In contrast, small-brained species such as mice typically have MLSPs of only one to two years. Yet there are notable exceptions: some mole rats can live up to about 20 years and many bats live far longer than their brain size alone would predict. Genomic analysis shows that these long-lived, small-brained species often carry expanded sets of immune-related genes.
These findings point to the immune system as a key contributor to longevity. Expanded immune gene families may help organisms maintain tissue health by removing damaged or senescent cells, limiting chronic infections, and reducing the incidence of tumor formation—processes that collectively slow physiological decline.
Importantly, the study emphasizes that shifts in lifespan are not explained solely by small-scale mutations. Instead, large genomic changes—such as the duplication and expansion of whole gene families—appear critical in shaping a species’ potential for long life. This perspective advances our understanding of how complex traits like longevity evolve through coordinated changes across the genome.
Dr Benjamin Padilla-Morales of the Milner Centre for Evolution and the University of Bath’s Department of Life Sciences led the research. He notes that while relative brain size has long been linked to lifespan—likely because larger brains confer behavioural and ecological advantages—the parallel expansion of immune-related genes suggests a coordinated evolutionary strategy that couples cognitive and physiological resilience.
The research team plans to follow up on cancer-related genes identified in this study to clarify how particular genomic changes influence lifespan differences among mammals. Their future work aims to untangle how immune function, cancer resistance and maintenance pathways together determine species-specific ageing trajectories.
About this longevity research news
Author: Chris Melvin
Source: University of Bath
Contact: Chris Melvin – University of Bath
Image: Image credit: Neuroscience News
Original Research: Open access. “Maximum lifespan and brain size in mammals are associated with gene family size expansion related to immune system functions” by Benjamin Padilla-Morales et al., Scientific Reports
Abstract
Maximum lifespan and brain size in mammals are associated with gene family size expansion related to immune system functions
Mammals show large variation in their maximum lifespan potential, measured as the longest recorded longevity of any individual of a species. Previous evidence links increases in lifespan to expansion in brain size relative to body mass. In this comparative study of 46 mammalian species, we detected significant expansions in gene family size associated with maximum lifespan potential and relative brain size, but not with gestation time, age at sexual maturity, or body mass.
Extended lifespan correlated with expanded gene families enriched for immune system functions, suggesting gene duplication within immune-related families is associated with the evolution of longer lifespans in mammals. These results illuminate genomic features linked to lifespan evolution and how they relate to life-history and morphological traits.